Primary prevention
Chemoprevention is recommended for women at high risk of developing breast cancer.[37][38][39][40]
Tamoxifen is indicated for chemoprevention in pre- and postmenopausal women. Raloxifene and aromatase inhibitors (e.g., anastrozole or exemestane) are recommended for chemoprevention in postmenopausal women only.[37][38][39][40] Some high-risk patients may choose to undergo prophylactic bilateral total mastectomy for breast cancer risk reduction. Risk-reducing mastectomy is usually considered for women if they have a pathogenic or likely pathogenic genetic mutation conferring a high risk for breast cancer, a compelling family history, or prior chest wall radiation at age <30 years.[37][41]
Assessing patient risk
Breast cancer risk reduction measures may be considered following evaluation using the National Cancer Institute’s Breast Cancer Risk Assessment Tool (the Gail model), which determines risk based on current age, age at first menstrual period, number of breast biopsies and whether atypical hyperplasia was found, age at first live birth, and number of first-degree relatives with breast cancer.[42] National Cancer Institute: breast cancer risk assessment tool Opens in new window
The Gail model applies to women aged 35-85 years. It is not accurate in the setting of prior DCIS, lobular carcinoma in situ (LCIS), invasive breast cancer, or BRCA1 or BRCA2 mutation. Risk may be underestimated in black women with previous biopsies and non-US born Hispanic women.
Other risk assessment tools are available (e.g., the BOADICEA model can be used for women with a known BRCA1 or BRCA2 mutation; the IBIS model can be used for women with prior LCIS).[43][44]
Lifestyle measures
Healthy lifestyle including physical activity and a balanced diet may prevent breast cancer.[45] In the Women's Health Initiative randomised controlled study, those who consumed a low-fat diet had a reduced risk of death after a diagnosis of breast cancer compared with those who consumed a usual diet.[46] The positive association between alcohol consumption and breast cancer risk is well established.[47] A study among patients attending breast clinics or screening found low levels of alcohol health literacy in this group. These appointments could provide an opportunity for discussing alcohol use as a modifiable risk factor.[48]
Secondary prevention
Avoiding hormone replacement therapy could reduce recurrence, new breast cancer, or progression of ductal carcinoma in situ (DCIS) to invasive breast cancer.[12][138] History of DCIS is a risk factor for future cancer in the same breast. Hormone replacement therapy (HRT) is not advised for this population. If DCIS develops during HRT, alternatives should be sought to treat menopausal symptoms.
Selective oestrogen receptor modulators such as tamoxifen can be used to prevent recurrence or new breast cancer.[119]
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Tamoxifen can be taken for up to 5 years.
In women at increased breast cancer risk, raloxifene has been shown to decrease the risk of new invasive breast cancer, but the benefit in reducing DCIS risk is less.[12] Thus, raloxifene has been approved by the US Food and Drug Administration in high-risk postmenopausal women and in women at risk for osteoporosis to prevent invasive breast cancer. Treatment with raloxifene for more than 4 years has been tested, and prolonged use does not appear to be harmful in the context of osteoporosis.[139]
Aromatase inhibitors have also been shown to decrease risk of recurrence after DCIS.
Women with lobular carcinoma in situ (LCIS) are considered high-risk (based on the Gail model) and should be offered chemoprevention to reduce the risk of invasive cancer, discussing the benefits and risks of the intervention. NCCN guidelines recommend tamoxifen for premenopausal women. Tamoxifen, raloxifene, exemestane, or anastrozole are options for postmenopausal women. The NCCN advises that tamoxifen is a superior choice of risk-reduction agent for most postmenopausal women.[37] However, consideration of adverse effects may lead some patients to choose raloxifene.
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